Inter-relationships between attention, activation, fMR adaptation and long-term memory.

fMR adaptation in the ventral visual pathway reflects information processing that may contribute to implicit and explicit memory. In experiments that employed <1 s repetition lag, we found that attention increases adaptation for repeated objects in brain regions at the top of the visual processing hierarchy (anterior fusiform and parahippocampal gyri) but that it can still appear with minimal attention in most of the fusiform bilaterally. Of the ventral visual regions showing adaptation, the parahippocampal region and LOC showed the strongest correlation between adaptation magnitude and recognition memory across subjects. Although there was some overlap, regions showing correlations between adaptation and priming lay more posteriorly within the fusiform region. The positive association between encoding-related activation and adaptation suggests that over an entire test set, memory performance can be determined by neural events occurring in the peristimulus period. This may reflect stronger engagement of attention at encoding.